Back in New York, Pratt — now a self-made scholar of respectable attainments — attacked more serious writing. After an abortive history of Alexander’s successors, he hit his stride with books like The Heroic Years, about the war of 1812, and Ordeal by Fire, a popular history of the American Civil War.

The Pratt menage in New York attracted a wide circle of friends, drawn by Pratt’s lavish hospitality and extraordinary sense of fun. One room of the apartment was cluttered with cages full of squeaking marmosets, which Pratt successfully raised by feeding them on vitamin tablets and squirming yellow larvae.

As a history, military, and naval buff, Pratt devised a naval war game, to which his friends were invited once a month. In odd moments, he had whittled out scale models (55 feet = inch) of the world’s warships, using balsa wood, wires, and pins, until there were hundreds of models crowding his shelves. The game called for the players to crawl around on the floor, moving their models the distances allowed on scales marked in knots; estimating ranges in inches to the ships on which they were firing; and writing down these estimates. Then the referees chased the players off and measured the actual ranges, penalizing ships hit so many points, according to the size of the shells, and depriving them of so many knots of speed, so many guns, and so on. When a ship had lost all its points, it was taken from the floor. There were special provisions for merchant ships, shore batteries, submarines, torpedoes, and airplanes.

For several years, the war garners met in the Pratts’ apartment. When this became too crowded, with fifty or more players at once, the games moved to a hall on East Fifty-ninth Street. After World War II, interest declined.

Pratt’s interests also included the reading of sagas and gourmet cookery. He wrote a cookbook, A Man and His Meals. He taught at the Bread Loaf Writers’ Conference, was a Baker Street Irregular, and served for seven years as president of the New York Authors’ Club. In 1944, he founded a stag eating, drinking, and arguing society, the Trap Door Spiders, which still meets periodically in New York.